Biological Theory of Ageing

Biological Theory of Ageing

The structural and functional status of the body's cells, tissues, organs, and systems—which governs growth, sturdiness, and mortality—is referred to as biological theory.

According to Morden, there are two major groups of biological explanations for human aging:

• Cellular theory

  • Cells have been a subject of much scientific inquiry in exploring aging phenomena . the cell has three distinct components
    • Cells that can reproduce :
      • Reproduction of cells occurs .Some new cells become nonfunctioning or less effective than the others that are replaced ( Busses, 1971). Three systems in the human body are continuously replaced ( skin, lining of the intestine , circulatory system). with the process in the aging process, there is an accumulation of these inefficient and nonfuctioning cells . organism functional ability becomes apparent . visible changes occur in the aging process.
    • Cells that cannot reproduce :
      • Eg. CNS, Kidney . With the age cells progressively wear and tear out and or destroyed. Develop an accumulation of non- functioning cells. System becomes less efficient and difficult to handle.
    • Intercellular substance/ materials:
      • Gradual deterioration of intracellular material with aging (Busse,1971) reduces the ability of the cells to provide necessary nutrient and oxygen for respective tissue and directly interfere the functioning abilities of each system.

• Programmed theory

  • Aging and death, according to this theory , are not a result of wear and tear or exposure but are a programmed to age and die .
    • Error theory
      • Mistranscription and mistranslation of certain genes products.n j
      • Reasult in self-amplifying error producing dearrangement (Struhler,1971)
      • The initial error will most likely reasult in further errors of similar types .
      • The productions of faculty products of other genes which accumulate with aging .eg. Enzymes with decrease catalytic activity in the later life.
    • Somatic mutation theory
      • Cells exposed to x-ray radiation or chemicals.
      • Cell by cell alteration in DNA occurs
      • Increase the incidence of chromosomal abnormalities
      • Occurs more at youth and its deleterious effect are seen in later life.
    • Wear and tear theory
      • Postulates that an organism " wears out" with use.
      • Damage begins at the level of molecules in our cells.
      • DNA that makes up our genes sustains repeated damage from toxins.
      • Bodies have the capacity to repair the damage but not all are accurately corrected .
      • Damage cells progressively accumulate.
    • Autoimmune theory
      • Postulates that with age , the immune system produces auto - anti bodies that cause cell death or cell changes that foster the aging process( WALFORD, 1969)
    • Free radical theory
      • Free radical is molecular with an unpaired , highly reactive electron. One type of free radical generated in our body is oxygen free radical .
      • This free radical grabs the molecule from any other molecule and damage the other molecule.
      • Molecules that are damaged by free radicals are Fat, protein and DNA .(both of nucleus and mitochondria).
      • Under normal condition natural defense mechanism prevent most of the oxidative damage.
      • This theory purposes that little by little small damage accumulates and contributes to deterioration of tissues and organs.
    • Cross-linkage theory
      • Also called as collagen theory.
      • With age, our proteins , DNA, and other structured molecules develop inappropriate cross-links to one another.
      • This unnecessary link decreases the elasity of proteins and other molecules.
      • Proteins that are damaged are no longer needed and are broken down by protease enzymes.
      • The presence of cross-linkage inhibits the activity if protease.
      • Damaged and unneeded proteins stick around and can cause a problem .Eg: wrinkling of skin at aging, age-related cataract formation.